An optical fiber ribbon cable comprises two or more parallel optical fibers that are joined together along their lengths. A material commonly referred to as a matrix adheres the fibers together. In an “encapsulated” type of ribbon cable, the fibers may be fully encapsulated within the matrix material. The rigidity of encapsulated ribbon cables presents challenges to achieving high fiber packing density, e.g., within an outer cable jacket. So-called “rollable” ribbon cables have been developed that can achieve high fiber packing density. In a rollable ribbon cable the matrix material is intermittently distributed along the fibers, providing sufficiently flexibility to roll up the ribbon cable about an axis parallel to the fibers.
A common type of rollable optical fiber ribbon cable comprises optical fibers that are each 250 μm (micrometers or “microns”) in diameter, spaced at a pitch (i.e., distance between the centers of adjacent fibers) of 250 μm. To increase fiber packing density without increasing cable size, 200 μm fiber having a bandwidth similar to the bandwidth offered by 250 μm diameter fiber has been developed.
A machine known as a mass fusion splicer can splice two ribbon cables without requiring an operator to separate the fibers. However, commercially available mass fusion splicers commonly have a fixed 250 μm pitch and cannot be used to splice ribbon cable having a 200 μm pitch.
It is possible to produce a rollable ribbon cable comprising 200 μm diameter fiber at a pitch of 200 μm. Such a ribbon cable thus has a 50 μm free space between each adjacent pair of optical fibers. To provide rollability, the matrix material is intermittently distributed along the fibers. Such distribution of matrix material allows an undesirable amount of lateral play or movement in the fibers, which may hamper aligning the ribbon cable in the 250 μm pitch grooves of the mass fusion splicer.